Average speed computing means



GROSS REFERENCE' G.'M. sxLLlNG AVERAGE SPEED COMPUTING MEANS Filed Dec. 4, 1933 yPt;genial Aug; 21'. Y1934 y l g1,971,2is

PATENT-OFFICE y y 1,911,238 AVERAGE srssn comme Mams Geom M. slum, cuboaale, 001. applicati@ December 4, 193s, serial No. 100,818

v (Chess-c1) v This invention relates to improvementsin rangement of the several parts in side elevation;

average speed computing means for use with automotivevehicles and other machines that move at a. variablespeed.

The ordinary speedometer employed with' auto- Y motive vehicles indicate the speed at any instant.v

but does not indicate-the average speed for any length of time.l l Y It is the object of this invention to' produce an instrument that will indicate the average speed for a period of time and which. when used in y connection with an automobile,` will give the'- average speed for any ordinary trip.

The speed at which an object moves is a'function of space and time and is equal to the distance traversed divided by the time. If the distence traversed in a time T is indicated by D andthe speed or time rate by V then V=D-:T.

odometer can be used to measure the distance traveled while a clock will measure the time and it therefore becomes necessary to invent an inv strument which shall be controlled both by a vfins clock and an odometer-in such a way that quotient of D-z-T can be read on a scale or dial.

It is well understood by mathematicians that 'division can be performed by means of logarithme and the difference between the log of the dividend and that of the divisor is the log of the quotient; thus, D-e-T =V is solved as follows:

log D-log T=log V.

In orderto perform mechanically the subtraction of the two logarithme in the manner indicated, it is only necessary to provide Ya scale hav- -ing the logarithms to the base 10 indicated thereonvand -to move the same by means of a cam in such a Way that the distance the scale moves corthis is accomplished by another cam which movesA H responds to the logarithm of the distance traveled by the vehicle; thedistance that the scale moves will then represent log D. To obtain the logarithm of V it is necessary to subtract from log D thello'garithm corresponding to the time T and the problem log D-log T=loggV.

'I'he apparatus that forms the subject of this yinvention will now be described in detail and for this purpose reference be had to the accompanying drawing in which it has been illustrated and in which:

Fig. 1 is a diagrammatic view showing the ar Fig. 2 is asection taken on line 2-2, Fig. 1;

Fig. 3 is a side view of the indicator showing'the scale and pointer in anotherv position;

' Y In the drawing numeral 6 designates the `'dial of an odometer which turns once for each mile traveled and reference numeral 7 designates ay clock. A shaft 8 is mounted for rotation in suitable bearings and has attached to oneend there-` ofa Spur gear that is in mesh with a pinion 10 secured to the same shaft as the odometer disk 6; gear 9 has ten times as many teeth as pinion 10 and the gear ratio is therefore 15 te 1.

cured to the opposite end of shaft 8 is a cam 11 whose cam surface is a logarithmic curve as will shaft 8 is a cam 12 whose cam surface is also a logarithmic curve, but whose radii are longer than Mounted for rotation on f the corresponding radii ofthe cam 11 by an amount equal to log 1U laid off on the scale used for cam 11. Cam l2 has a hub 13 to one end of which is secured :a spur gear 14, a spur gear 15 is secured to shaft 8 and this is in mesh with an identical spur gear 16 secured to shaft 17. Attached to shaft 17 is' a pinion 18 that is in mesh with spur gear 14 which has ten times as many teeth as the pinion 18. Since gears 15 and 16 are the same size, shaft 17 will rotate at the same speed as shaft 8 and since pinion 18 has onetenth as many teeth as spur gearl, cam 12 will rotate one-tenth as fast as cam 11, but in the same direction. f

Clock 7 has an hour spindle 19 and a minute spindle 20. A' cam 12a, which is similar to cam 12, and a cam 11a, which is similar to cam 11, are connected respectively to the hour spindle 19 and the minute spindle 20; cam 11a will therefore make one complete revolution in one hourand cam 12a a complete revolution in twelve hours.

Located to one side of cams l1 and 12 are ltwo guides 21 and 22 between which is mounted a flat slide 23 on the surface of which is plotted a vlogarithmic curve 24. Another slide 25 is also mounted in the guides 2l and'22 and lies in contact with the surface of slide 23. The straight so Y edge 26 ofthe slide 25 serves to indicate the readv ing by its position on the curve 24. A pusher oar 27 has one end attached to the slide 23 and has its other end bent at right angles to form a pin 2,8 which extends across the planes ofboth cams 11 so n' and 12. A tension yspring 29 has one end attached to the slide 23 and serves to hold the pin 28 lagainst .the periphery. of the cam with which it cooperates. A pusher bar similar to pusher bar 2'?, has one end attached to the slide 25 and the other bent to form a pin 31 that vcorresponds to pin 28 on bar. 2'?.V Pin 3l cooperates with cams 11a and 12a andmoves the straight edge Aagainst the tension of thespring 32 whenithe cams are rotated bythe clock-.- v.

Cams 11 and 11a are identical in size and shape Y and cam 11 turns once whilel thevehicle travels ten miles while cam 11a turns once in one hour;

Cam 11 has its point of origin at 33, which is as close to the center as possible because the distance from the center to the periphery represents the log of one, which is aero; it is not practical to cut away all ofthe metal and this point is therefore not accurately located. When the 4vehicle has traveled two miles the point marked 2 will be in contact with pin 28 and since the distance from I. the center to the periphery is the log of 2, to the scale employed', the slide 23 will be moved towards the left a distance equal to the log of 2 and if the straight edge remains stationary, the point on f curve 24 will intersect line 26 at 20.

' If the time controlled cams are set in motion V.at the same time that the vehicle starts, cam

through'an angle of 36 degrees and the pin 28v will be transferred to the periphery of cam 12. When cam 11a has made'one complete turn, pin

, 31 will be transferredto the periphery of cam 12a..- Cams 12 and 12a are the same shape as `cams 11 and 11a, respectively, and differ from them merely in this, that the corresponding radii of cams 12 and 12a are longer by thevlogarithm of 10 to the scale employed.

It is evident that when the vehiclemoves, the instrument will continue to subtract the log of the number of hours elapsed fromthe log of the A number of miles traveled and the difference can be read on the scale 23.

In Fig. 3 the position of the scale and the straight edge have been shown at the end of onehalf an hour and after the vehicle has traveled twenty miles, the position of the parts shown in Fig. 3 will also bel the lsaine if the vehicle has traveled eighty miles in two hours.

Il the vehicle stands still the straight edge will continue to be moved by the clock operated cam and will reduce the average speed for the trip.

Aince the scale on the straight edge has equal divisions, Vit is evident that it can be replaced by an electrical resistance 25a and that a metal conductor 24a can be bent to correspond to the curve 24. If'the resistance and the electrical conductor are so positioned that they will. always be in Contact at the point of intersection', the resistance of theportion X will represent the average speed. It an ammeter AM and a battery B areccnnec'ted in series with the resistance 25ct and the conductor 24a the current iiowing through the ammeter will vary directly 'with X and the average speed.

In Fig. 5 an arrangement .has been shown in which the axes about which cams 11, 12 and 11a, 12a rotate arealigned and thisis the preierable construction. The arrangement illustrated in Figs. 1 and 2 is merely for convenience 8o explaining the invention and its operation;

In the claims, the term logarithmic cam" will be used and this refers to a cam whose peripheryv is a. curve whose radii are the logarithms of numbers from zero to l0 or such logarithms plus 85 the distance corresponding to the characteristic of the number.

. Attention is called to the fact that if the clock operated cams are not operating the device becomes an odometer and registers the distance traveled only.

In the drawing the vehicle has not been shown; but the odometer disk 6 is driven directly from the vehicle and is therefore to be considered as part of the vehicle and represents the latter in g5" the disclosure.

In the above part of'l the specirlcatiomthe statement is made that cams 12 and 12a are similar. This refers tothe fact that the length of the radii corresponding to the same number of miles 10d n i y and hours are of equal length, but since cam 12 makes one revolution in ten miles, while cam 12a makes one revolution in twelve hours, the space between-adjacent unit radii 4is 36 degrees in the former and 3U degrees in the latter. rithms of 11 and -12 hours is, of course, greater than the log of 10 and therefore cam 12a is slightly larger than cam 12, due to the contracy tion of the unit spaces.

Having described the invention what is claimed no as new is:

1. An instrument for determining the average speed of travel of a vehicle comprismg. in c .m-

binatiom a member which is rotated through an angle proportional to the distance traveled, a l logarithmic cam operatively connected to the said member by means which produces a complete rotation of the cam while the vehicle travels ten miles, a second logarithmic cam mounted for rotation about an axis concentric with the 129 axis of the rst cam, means interposed between the rotatable member and the second cam for rotating it at one-tenth the speed of the iirst cam, the radii or the second cam being longer than the corresponding radii of the first cam by an amount equal to the logarithm of 10 to the scale employed, a movable member provided with a curve whose ordinates and abscesses are respectively numbers and their logarithms, means for moving the member having the curve, com- 130 prising apush bar and a pin that extends across the planes of the cams, two other logarithmic cams mounted to rotate about a common axis, and both driven from a clock, the smaller cam rotating once each hour and the larger one once every twelve hours, a straight edge mounted for relative movement with respect to the curve on the movable member, and means compring a .push bar and a pin for moving the pointer, the pin extending across the planes of both cams M@ whereby it will be moved first by the smaller cam and then by the larger cam.

2. An instrument for determining the average speed of a vehicle which travels at a variable speed comprising, in combinatioma logarithmic y cam rotated through an angle proportional to the distance traveled by the vehicle, a smaller logarithmic cam mounted to rotate about the same axis as the iirst cam but at a rate ten times as fast as therst cam, the two cams being so re- I 4fast as the rst cam, the two cams beingso re. lated that the radii of the rst and larger cam lated that` the ofthe iirst and larger cam are longer than thecorresponding radii of `the smaller cam .by an amount equal to the logarithm of 10` to the scaleaemployed, a.v logarithmic scale mounted for movementV in a plane, means operatively associated with the curve andv the cams for moving it rst in response' to the smaller camV and "then in response to the movement of the larger cam, a-movable straight edge operatively associated with the curifre,l a logarithmic time controlled ycam constructed to the same scale as the other cam, a clock mechanism for rotating lthe time controlled cam, and means for mov ing the straight edge in accordance with the time controlled cam whereby the position of the straight edge relative to the curvev will indicate the logarithmof the average speed of the vehicle :for the time elapsed.

3. An instrument for determining the average speed of a vehicle which travels at a variable speed comprising, in combination, a logarithmicv cam' rotated through an angle proportional tothe distance traveled by the .vehicleya smaller logarithmic cam mounted to rotate about the same' axis as the rst cam but lat a rate ten times as are longer than the corresponding radii of the smaller cam by an amount equal to the logarithm or 1o to the scaievempioyed, 'a logarithmic scale mounted for movement in a plane', means operaand then in response to the movement ofthe largerca m, a clock mechanism having airhour hand. spindle that rotates 360 degrees in twelve tively associated with the curve and the cams for moving it iirst in response to the smaller cam hours and a. minute spindle that rotatesv 360 degrees in one hour, a logarithmic cam constructed s l to the same scale as the rst mentioned cam and secured to the hour spindle so as to rotate there with the radii of the cam representing the logarithmsof numbers from zero to twelve spaced so as to embrace a complete circle, a smaller logarithmic cam secured to the minute spindle so;A

as to rotate therewith, the radii of the last mentioned .camrepresenting the vlogarithm of the numbers from zero to sixty, the' scale being such that the radius of the smaller time controlled cam representingy sixty minutes is equal to the radius of the larger time controlled cam which f represents one hour, a straight edge movably associated with the curve and means for moving the no g 

